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Tropical Storm LESTER Forecast Discussion

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WTPZ43 KNHC 262032

200 PM PDT FRI AUG 26 2016

After the convection associated with Lester appeared to be rather
shapeless in infrared satellite imagery overnight, visible pictures
indicate that there has been a significant increase in organization
today. Although the convective clouds tops are not very cold, a
ragged banding eye feature has become apparent within the past
couple of hours.  As a result, Dvorak T-numbers have risen to 4.0
and 3.5 from TAFB and SAB respectively, and the initial wind speed
has been increased to 60 kt for this advisory.  The center has
passed about 50 n mi southwest of Clarion Island during the past few
hours, and a weather station on that Island has reported sustained
winds of 46 kt with a gust to 62 kt.

Lester is forecast to move over warm water and within a low shear
environment during the next 2 to 3 days, which should result in
steady strengthening.  Late in the forecast period, slightly cooler
waters and less favorable thermodynamic conditions are likely to
induce some weakening.  The NHC
forecast calls for Lester to become a hurricane tonight, which is
in line with most of the intensity guidance.  Later in the period,
the NHC wind speed prediction is a little above the intensity
consensus and SHIPS guidance, but is in good agreement with the
Florida State Superensemble.

Recent satellite fixes and ASCAT data indicate that Lester is
centered a little north of the previous position, and the latest
initial motion estimate is west-northwestward at about 6 kt.  The
forecast track reasoning remains unchanged as a strong mid- to
upper-level ridge is forecast to remain over the eastern Pacific to
the west of the Baja California through the middle of next week.
Lester is expected to turn almost due westward by Saturday and
remain on that heading during the next 5 days.  The track guidance
remains in excellent agreement, but the more northward initial
position required a northward adjustment to the NHC track forecast.

The wind radii have been adjusted outward based on the observations
from Clarion Island and recent ASCAT data.


INIT  26/2100Z 17.6N 115.8W   60 KT  70 MPH
 12H  27/0600Z 17.8N 116.9W   65 KT  75 MPH
 24H  27/1800Z 17.9N 118.7W   70 KT  80 MPH
 36H  28/0600Z 18.0N 120.9W   75 KT  85 MPH
 48H  28/1800Z 18.0N 123.3W   80 KT  90 MPH
 72H  29/1800Z 18.0N 128.7W   80 KT  90 MPH
 96H  30/1800Z 18.0N 134.2W   80 KT  90 MPH
120H  31/1800Z 18.0N 139.5W   75 KT  85 MPH

Forecaster Brown